This invention relates to a method and apparatus for a dishwasher. More specifically, this invention relates to a dishwasher having a control system that provides for variable fill control.
Dishwashers conventionally have provided for the filling of an inner chamber of a dishwasher with water. As disclosed in U.S. Pat. No. 5,806,541 to Cooper, et al., electrically controlled water valves are turned on for one or more periods of time during a wash cycle. Thus in the prior art, the fill of a dishwasher is provided for by turning on a water valve for a set period of time. This period of time is determined by the manufacturer.
One problem with this prior art approach is that the flow rate through the water valve is not necessarily constant. The flow rate of the water valve may be different from the flow rate of the water valve that was used in the dishwasher""s design. Furthermore, there may be differences in water pressure from one installation of the dishwasher to another. These differences in the flow rate result in differences in the volume of water that fills a dishwasher. If the dishwasher is under filled with water then items within the dishwasher may not be thoroughly cleaned. If the flow rate is greater than anticipated, then the dishwasher has a greater fill volume than designed for which can result in a waste of water resources as well as unanticipated or undesirable effects on the dishwashing process.
Therefore, it is a primary object of the present invention to provide a method and apparatus for a dishwasher that improves over the state of the art.
It is a further object of the present invention to provide a method and apparatus for a dishwasher that does not need to rely upon fill times that are predefined by a manufacturer.
Yet another object of the present invention is to provide a method and apparatus for a dishwasher that provides for variable water fill volumes without requiring multiple water fill level detectors and without directly sensing water fill rate.
A further object of the present invention is to provide a method and apparatus for a dishwasher that prevents the maximum fill volume of the dishwasher from being exceeded.
Yet another object of the present invention is to provide a method and apparatus for a dishwasher that reduces the effects of disturbances in water supply pressure.
These and other objects, features, or advantages of the present invention will become apparent from the specification and claims that follow.
The present invention is a method and apparatus for a dishwasher having a control system that provides for variable water fill volumes. The dishwasher control system includes a fill volume sensor for sensing that the dishwasher has reached a known fill volume. The dishwasher control system also includes a timer for timing a period of time between the beginning of a fill and the point in time where the known fill volume has been reached. An intelligent control is electrically connected to the fill volume sensor and is operatively connected to the timer. The intelligent control is adapted for calculating a dishwasher fill rate.
Once a fill of the dishwasher begins, the fill continues until the fill volume sensor senses that a known fill volume of the dishwasher is reached. Based on the amount of time between the starting of the fill of a dishwasher and the time at which a known fill volume of the dishwasher is reached, a fill rate is calculated. This fill rate can be used in several different ways. For example, the dishwasher can then be filled with an additional volume of water. This additional volume of water is provided for by calculating an additional period of time at the calculated fill rate. In addition, the calculated fill rate can be averaged with other calculated fill rates in order to determine an average dishwasher fill rate and this average dishwasher fill rate can be used to calculate the amount of time necessary for additional or continued fill.
Thus, the present invention provides the benefits, features, and advantages of providing for proper fill volumes. The actual fill rate of a particular dishwasher installation may vary with water pressure or other factors. The present inventions considers the actual amount of time to reach a predefined fill volume instead of relying on a manufacturer predefined time period. In addition, only one sensor is needed to determine water level or fill volume.